Calculation and analysis for the time-dependency of settlement of the single-driven pile in double-layered soft clay

• Changes of pore water pressure with horizontal direction and depth are considered.
• The method is derived from three-dimensional dissipation mode.
• The method can be applied in homogeneous and double-layered soft clay.

The dissipation of the pile-side excess pore water pressure caused by pile driving is the main cause of the settlement of single-driven pile in soft clay. Based on the three-dimensional consolidation theory, the calculation formula for reconsolidation settlement of pile-side soil was derived. In addition, the calculation formula for the settlement of the single-driven pile caused by the pile-side soil reconsolidation settlement was derived using the pile–soil interaction principle and by combining boundary conditions in double-layered soft clay. An engineering example was also calculated and analyzed. The research shows that the settlement of the single-driven pile caused by the dissipation of pile-side excess pore water pressure is larger and is far more than that caused by the vertical load. Thus, the settlement of the driven pile was larger than that of the bored pile. The research also indicates that the settlement of the single-driven pile increases with time because of the influence of the pile-side soil reconsolidation, and then it gradually becomes stable.